The annoyance is that most everyone DOES take Solo cards, but National Rail is the biggest notable exception to this.
Also, it's not as simple as requesting an upgrade to Maestro and getting it...you have to qualify first! I've tried twice now to upgrade my NatWest account from Step to Current and despite being a member since 2004, I still can't until I have a decent full-time permanent job! The Solo card is generally okay and not too much a hinderance, but it's a right pain in the butt when you need to buy a £2 train ticket and have to take £10 out via ATM to pay for it! Even McDonald's takes Solo cards :-P